[NikkiA]

I dunno, '700 AU' gelled for me instantly, '15 times the distance to pluto' doesn't even make sense given pluto's orbit isn't anywhere near circular.

[AIPedant]

It makes even less sense for Earth because Earth's orbit is near-circular, whereas Planet 9's hypothesized orbit is highly eccentric, more so than Pluto.

Most people don't know off-hand that Pluto is ~40-50AU from the sun, so 700AU is hard to conceptualize.

[zamadatix]

They're all horrible to conceptualize because people don't commonly deal with how far even something like the Earth to the Sun is, I don't think there is any winning answer here - at least an AU is consistently defined and maybe slightly more likely to be familiar, but it's still just about as crap to be honest.

Side note: Apart from AU already being defined as average distance and not current distance, the distance referenced is how far out the proposed object is now, not its general orbital parameters. At that orbital distance 23 years of motion isn't going to be much change in distance even if it's in a hyperbolic orbit.

[d0mine]

To give perspective to 700AU: the nearest star is ~270 kAU i.e. the object is at ~0.26% (close to the Sun)

https://imagine.gsfc.nasa.gov/features/cosmic/nearest_star_i...

[dragonwriter]

> Most people don't know off-hand that Pluto is ~40-50AU

~30-50AU if you are referring to the range of orbital distance.

[LeifCarrotson]

And Neptune orbits at 30 AU with very low eccentricity, "of course."

https://xkcd.com/2501/

[doubletwoyou]

I don’t think the vast majority of people will have a good sense of how far away the standard gas giants and pluto are from the sun in terms of AU.

[nandomrumber]

The length of 2.1 trillion Olympic swimming pools.

Or 698 trillion bananas.

[nmeofthestate]

It helps if you picture Planet 9 orbiting on the surface of a sphere with the surface area of 6.6349344e+18 Waleses.

[MisterTea]

I only understand American football fields :-<

[Waterluvian]

On its own it’s a bit of a useless number. You’d have to know how many AU Pluto is to understand context.

But if you got “15x further than Pluto” you have context without needing to know any other trivia-style numbers.

[wqaatwt]

AU is not exactly a trivia style number. It’s one of the most standard units of measuring distance between different bodies in space.

Also it’s not like distance to Pluto is a meaningful number either since it’s extremely variable . AU at least is fixed

[bryant]

New horizons launched 9.5 years before it reached Pluto, and your average reader who has an interest in Planet 9 will likely know it took New Horizons about that long.

15x means no one alive today will see a mission that reaches the planet, and that's more accessible for most readers per above.

[Retric]

New horizons is hardly the fastest possible probe over the next 30 years.

(9.5 * 15 / 3 = 47.5) + 30 years = 77.7 so some teenagers could live to see a probe reach it even without hypothetical life extension technology.

[rkagerer]

1 hour at Warp 4

[mrguyorama]

Original formula or Next Generation formula?

[cdaringe]

Ahem, cite your sources? At low warp we’re generally BLASTING by stars!

[ashoeafoot]

Are we there yet?